Mobility is a fundamental precondition in most modern wireless communication networks. Accordingly, most wireless communication systems comprise mobile nodes (e.g. cell phones or similar) and radio access nodes (e.g. base stations or similar) configured to operatively provide wireless communication for the mobile nodes in the wireless communication system.
Well known examples of wireless communication systems comprising mobile nodes or similar can be found in the Global System for Mobile communications (GSM), the General Packet Radio Service (GPRS), the Wideband Code Division Multiple Access (WCDMA), the High Speed Packet Access (HSPA), Long Term Evolution (LTE) and other cellular technologies or similar intended for a more or less global access. Other examples of systems comprising mobile nodes or similar can be found in the Worldwide Interoperability for Microwave Access (WiMAX) and other wireless communication networks or similar intended for more or less local or regional access.
A radio access node in such wireless communication systems as those exemplified above or similar is typically configured to communicate with a plurality of mobile nodes in the coverage area of the access node (e.g. within a cell covered by the radio access node). A mobile node in the coverage area of a radio access node may be active or idle. Active mobile nodes are typically known to the communication system at radio access node level. For example, the core network or similar of the system may have information about the geographical location of a mobile node based on the geographical location of the radio access node in question. As a contrast, idle mobile nodes may only be known by the core network at a higher level, e.g. on a paging group level or tracking area level or similar. In other words, idle mobile nodes are typically not known at radio access node level.
For each active mobile node there is a mobile node context. The mobile node context may e.g. be set up and/or held by the radio access network (e.g. a radio access node) and/or the core network or similar of the wireless communication network. The mobile node context of a mobile node may e.g. comprise the identity and/or properties of the mobile node and/or the capabilities and services that have been set up for the mobile node etc. More generally, the mobile node context for a specific mobile node contains the necessary information needed for the radio access node to communicate with the mobile node. An example of a mobile node context is the so-called user equipment (UE) context defined within the framework of the specifications provided by the 3GPP (Third Generation Partnership Project, see e.g. www.3gpp.org). A mobile node context of some sort can be found in almost every modern wireless communication systems, e.g. as those exemplified above or similar. The typical constitution and use of various mobile node contexts or similar is well known to those skilled in the art and it needs no further explanation.
If the operation of a radio access node serving a plurality of mobile nodes fails such that the radio access node has to be restarted the mobile node context for all or a majority of the served mobile nodes may be lost. As a consequence, a majority of the served mobile nodes may have to renew their association with the radio access node and reestablish their mobile node context respectively. This is applicable to wireless communication networks in general and to cellular wireless communication networks in particular. In a typical scenario there may be several hundred mobile nodes located within the range of and served by a radio access node.
A schematic illustration is provided in FIG. 1 showing an exemplifying wireless communication system 100 comprising a radio access node 110 (e.g. a base station) with a schematic coverage area (e.g. cell) defined by the radius R1, and a plurality of mobile nodes 120 (e.g. cell phones). In case of a restart of the radio access node 110 there may be several hundred mobile nodes accessing the radio access node for a renewed association and a reestablished mobile node context.
The association of a mobile node 120 with a radio access node 110 requires a number of resources in the radio access node 110. Most notably, the association requires an initial access capacity and a payload capacity to be provided. The initial access capacity is required for the initial network entry, whereas the payload capacity is required for continued access to the network resources. The features of access and payload capacity are well known to a person skilled in the art and they need no further description.
There is always a tradeoff between the initial access capacity for network entry and the payload capacity (e.g. reserved for transmission of data such as payload and control signaling). The initial access capacity for network entry is typically dimensioned for a steady-state scenario with a few entry events per second. This is done to avoid any waste of capacity that can be used for payloads.
However, a low capacity for the initial access function is not adequate if a large number of mobile nodes 120 are accessing a radio access node 110 for a network entry in a short period of time. This is particularly so in a restart scenario as described above. A low capacity for the initial access function will then increase the time required for the mobile nodes 120 to renew their association and mobile node context, which decreases the probability that a service provided to a particular mobile node can be upheld by the wireless communication system 100. In addition, a low capacity for the initial access function will also increase the risk that the radio access node 110 may not detect all the accessing mobile nodes 120. On the other hand, if the initial access capacity is high, the capacity for payloads will be unnecessarily reduced during ordinary operations (e.g. in a steady-state scenario).
Hence, in view of the above there seems to be a need for improvements directed to the capacity allocated to initial access for network entry and the capacity allocated to payloads in a wireless communication system.